feat(tests): updated tests coverage to 66.5%

test/features/settings/models/oauth_attach_request_test.dart

@@ -78,5 +78,36 @@ void main() {
       expect(googleRequest.provider, 'google');
       expect(facebookRequest.provider, 'facebook');
     });
+
+    test('toJson serializes OAuthAttachRequest correctly', () {
+      const request = OAuthAttachRequest(
+        provider: 'google',
+        clientId: 'client123',
+        accessToken: 'access_token_123',
+        refreshToken: 'refresh_token_123',
+      );
+
+      final json = request.toJson();
+
+      expect(json['provider'], 'google');
+      expect(json['client_id'], 'client123');
+      expect(json['access_token'], 'access_token_123');
+      expect(json['refresh_token'], 'refresh_token_123');
+    });
+
+    test('toJson serializes OAuthAttachRequest with null clientId correctly', () {
+      const request = OAuthAttachRequest(
+        provider: 'facebook',
+        clientId: null,
+        accessToken: 'access_token_456',
+        refreshToken: 'refresh_token_456',
+      );
+
+      final json = request.toJson();
+
+      expect(json['provider'], 'facebook');
+      expect(json['access_token'], 'access_token_456');
+      expect(json['refresh_token'], 'refresh_token_456');
+    });
   });
 }